The police interview was played to the High Court at Auckland today on day four of Banks' trial for filing a false electoral return.
Banks told police he was an "honest trader, straight up, straight down".
"I don't believe I've done anything dishonest, in inverted commas, in my life."
The former mayor, who went on to make a return to parliament as Act leader, also told police in the interview that his campaign workload was "mind-bending".
"Every morning, every afternoon, every night, every day for 18 months, the work load was mind-bending. I'd never do it again, especially if I knew I was going to lose ? back-breaking, mind-bending."
He wrote "hundreds" of letters to people who made financial contributions to his campaign, he said.
"I thought that was important because we wanted to go back to those people again for more money if we needed it."
Banks is defending a charge of filing a false electoral return by knowingly receiving political donations from Dotcom and SkyCity that were recorded as anonymous.
Banks said he flew to Dotcom's Coatesville mansion in a helicopter to meet him in 2010.
In June that year Banks and his wife Amanda returned to the mansion for lunch, along with business people and other "hangers on".
"I called [Dotcom] aside and I went to his conservatory," Banks said. There, flanked by a 600 kg steel statue of a fighting warrior, Banks asked Dotcom for financial support.
"He offered me $200,000, plus he said, 'I could give you quite a lot of access to social media'."
Banks asked for $25,000. He couldn't recall if Dotcom said 'yes' or 'no' but said he told Dotcom he could make more than one $25,000 donation from different entities.
Dotcom has said Banks asked him to split an offer of $50,000 in half, so to keep his support anonymous. But Banks told police: "Oh no no no no no. That's humbug."
He said he couldn't remember ringing Dotcom to thank him for his donation.
Banks said the electoral return was prepared by his campaign treasurer Lane Hutchison. When asked what his obligations were in checking the information in the return, Banks' reply was that he had confidence in Mr Hutchison.
The allegations against Banks relate to two $25,000 donations from Megastuff Ltd on Mr Dotcom's behalf in June 2010 and $15,000 from SkyCity in May that year.
The trial resumes on Monday when Mr Morrison, the final prosecution witness, is due to give evidence.
